2010-08-25

Newly discovered microbe helped disperse oil, study finds

(CNN) -- A new study finds oil spilled into the Gulf of Mexico from a ruptured BP well degraded at a rate that was "much faster than anticipated," thanks to the interaction of a newly-found and unclassified species of microbes with the oil particles.

Berkeley Lab's Earth Sciences Division and the Energy Biosciences Institute examined a dispersed oil plume that was formed at a depth of between 3,600 and 4,000 feet and extended some 10 miles out from the wellhead.

"Our findings show that the influx of oil profoundly altered the microbial community by significantly stimulating deep-sea psychrophilic (cold-temperature) gamma-proteobacteria that are closely related to known petroleum-degrading microbes," said Terry Hazen, a microbial ecologist and principal investigator on the study.
The cold-temperature bacteria "appears to be one of the major mechanisms behind the rapid decline of the deepwater dispersed oil plume that has been observed," Hazen said.

Researchers believe the light, sweet, nature of this particular crude, plus the Gulf's hardy adaptation to "frequent episodic leaks from natural seeps" may have contributed to its improved microbial ability to break the oil down.
The use of Corexit, a controversial commercial oil dispersant widely used during operations in response to the BP oil spill, "may have also accelerated biodegradation because of the small size of the oil particles and the low overall concentrations of oil in the plume," according to the study.

Additionally, the report noted the microbial degradation of the oil appeared to "take place without a significant level of oxygen depletion." Scientists had been concerned the microbes would consume large portions of oxygen in plumes, creating "dead zones" where it would be difficult to sustain sea life. The study found that oxygen saturation outside the plume was 67 percent while within the plume it was 59 percent, only a slight drop.

Hazen said the report is "the first data ever on microbial activity from a deepwater dispersed oil plume," and the microbes' speedy rate of degradation showed that the bacteria plays "a significant role in controlling the ultimate fates and consequences of deep-sea oil plumes in the Gulf of Mexico."

Scientists began the study on May 25, just a little more than a month after the Deepwater Horizon rig exploded, killing 11 workers and precipitating the world's largest accidental oil spill.

According to Berkeley Lab, the Gulf of Mexico's deep waters are a relatively unexplored microbial habitat, where temperatures hover around 5 degrees Celsius, the pressure is enormous, and there little carbon is normally present.
The findings of the report will appear in the journal Science on Thursday.